This invention relates to an electronic postage scale and, in particular, to an improved postage scale wherein postage data is automatically determined and displayed in response to the weight of a parcel and in accordance with a selected class of shipment and destination zone forthat parcel.
Generally, in computing the requisite postage for a parcel to be mailed to a desired destination, such postage is not only dependent on the weight of the parcel but, in addition, depends upon the particular destination zone and the class of shipment that is desired. Typically, four distinct classes of shipment are available, each being associated with a unique postage rate. The four well-known classes of shipment are priority, parcel post, book rate and UPS.
Prior to the advent of automatic postage calculating devices, an individual would determine the proper postage by first weighing the parcel to be shipped and, once the weight of that parcel had been determined, a reference table associated with the selected class of shipment was consulted and the indicated postage for the desired destination zone was recorded. A comparison of postage rates for each class of shipment required that the individual refer to each reference table and record the corresponding postage obtained therefrom. It was fully appreciated that this technique of computing postage was not only time consuming but was subject to various errors that inadvertently could occur during the nrmal usage of such reference tables.
Accordingly, the introduction of automatic postage scales and calculating devices evidently met a definite need. One such prior art automatic postage scale is disclosed in my U.S. Pat. No. 3,738,438, assigned to Better Packages, Inc., the assignee of the present invention. This postage scale uses digital techniques to automatically provide an indication of the postage required for a selected class of shipment to a desired distance zone in accordance with the weight of the parcel to be shipped. The postage data for each class of shipment and destination zone are provided as coded perforations in an adjustable postage code roll. That is, the postage codes are arranged on the roll in a plurality of groups, each group representing the postage rates for a particular combination of distance zone and class of shipment. An operator advances the roll to select the proper rate group. When the proper rate group is selected, it consists of a plurality of sets of further codes representing the postage for various parcel weights in the selected rate group. The particular data set is detected in acccordance with the weight of the parcel and the postage represented by that data set is read out and displayed.
Although this prior art postage scale functions satisfactorily and has been favorably accepted, various features thereof can be readily improved. For example, the use of an encoded postage data roll requires that an operator, or auxilliary automatic apparatus, advance the roll until the proper rate group representing a predetermined class of shipment and a desired destination zone is obtained. This, of course, requires careful supervision by the operator and further requires the use of a bulky data roll that occupies space which could otherwise be advantageously used. Hence, the total time required to determine the requisite postage for a parcel, although significantly reduced from that theretofore required, can be still further reduced. Also, this scale does not fully exploit the total automation capabilities of automatic postage scales.
In another prior art postage scale employing digital techniques, an electronic memory is provided along with a complex data processing section. Postage data that is stored in the memory is read out therefrom in accordance with a complex address signal generated by the data processing section as a function of a parcel weight, class of shipment and destination zip code. The use of a data processing section adds to the cost of construction of such postage scale and adds complexities that, unfortunately, can provide a source of erroneous operaton. Furthermore, postage scales of this type are subject to false postage determinations in the event of improper calibration.